package com.fish.sqlSession;

import com.fish.config.BoundSql;
import com.fish.pojo.Configuration;
import com.fish.pojo.MappedStatement;
import com.fish.utils.GenericTokenParser;
import com.fish.utils.ParameterMapping;
import com.fish.utils.ParameterMappingTokenHandler;
import com.mysql.cj.util.StringUtils;
import com.sun.org.apache.xpath.internal.operations.Bool;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

public class SimpleExecutor implements Executor {

    private PreparedStatement getPreparedStatement(Configuration configuration, MappedStatement mappedStatement, Object... params) throws SQLException, ClassNotFoundException {
        //1.获取数据库连接（这里报错了dai）
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql语句
        String sql = mappedStatement.getSql();
        //将sql中的#{}替换成?
        BoundSql boundSql = getBoundSql(sql);

        // 3.获取预处理对象：preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getParseSql());

        // 4.设置参数
        String paramterType = mappedStatement.getParamterType();

        // 通过反射取得参数
        Class<?> paramtertypeClass = getClassType(paramterType);
        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappings();
        for (int i = 0; i < parameterMappingList.size(); i++){
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();
            if(StringUtils.isNullOrEmpty(paramterType)){
                preparedStatement.setObject(i+1,params[i]);
            } else {
                Field declaredField = null;
                try {
                    declaredField = paramtertypeClass.getDeclaredField(content);
                    //暴力访问
                    declaredField.setAccessible(true);
                    Object o = declaredField.get(params[0]);
                    preparedStatement.setObject(i+1,o);

                } catch (NoSuchFieldException | IllegalAccessException e) {
                    e.printStackTrace();
                }
            }
        };
        return preparedStatement;
    }


    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {

        PreparedStatement preparedStatement = getPreparedStatement(configuration, mappedStatement, params);
        ResultSet resultSet = preparedStatement.executeQuery();
        String resultType = mappedStatement.getResultType();
        Class<?> resultTypeClass = getClassType(resultType);
        ArrayList<Object> objects = new ArrayList<>();

        // 6. 封装返回结果集
        while (resultSet.next()){
            Object o =resultTypeClass.newInstance();
            //元数据
            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i = 1; i <= metaData.getColumnCount(); i++) {
                // 字段名
                String columnName = metaData.getColumnName(i);
                // 字段的值
                Object value = resultSet.getObject(columnName);

                //使用反射或者内省，根据数据库表和实体的对应关系，完成封装
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o,value);
            }
            objects.add(o);

        }
        return (List<E>) objects;
    }

    @Override
    public boolean insert(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        PreparedStatement preparedStatement = getPreparedStatement(configuration, mappedStatement, params);
        return preparedStatement.execute() ;
    }

    @Override
    public int update(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        PreparedStatement preparedStatement = getPreparedStatement(configuration, mappedStatement, params);
        return preparedStatement.executeUpdate();
    }

    @Override
    public boolean delete(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        PreparedStatement preparedStatement = getPreparedStatement(configuration, mappedStatement, params);
        return preparedStatement.execute() ;
    }

    private BoundSql getBoundSql(String sql) {
        //标记处理类：配置标记解析器来完成对占位符的解析处理工作
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{", "}", parameterMappingTokenHandler);
        //解析出来的sql
        String parseSql = genericTokenParser.parse(sql);
        //#{}里面解析出来的参数名称
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();

        BoundSql boundSql = new BoundSql(parseSql,parameterMappings);
        return boundSql;
    }

    private Class<?> getClassType(String paramterType) throws ClassNotFoundException {
        if(paramterType!=null){
            Class<?> aClass = Class.forName(paramterType);
            return aClass;
        }
        return null;

    }
}
